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As a “green chemistry” tool, ultrasound irradiation of high intensity was successfully applied to formation of cerium /aluminum oxide anticorrosion protective layers on metal surfaces. The mechanism of metal surface modification in the presence of cerium(III) aqueous solution results from two components: activation of the metal surface by localized heating and activation of cerium ions which are diffused within liquid jets at high velocity to the metal surface. The ultrasonically increased reactivity of cerium and the developed surface of the metal stimulate formation of a novel type of cerium-enriched protective layer: cerium/aluminum oxide nanonetwork, where cerium oxide and aluminum oxide are interlaced in a mixed layer strongly connected to the metal surface. A combination of microscopic and spectroscopic methods was applied to study structure and morphology of the coatings as well as to optimize the ultrasound-assisted preparation method. The anticorrosion activity of the novel cerium/aluminum oxide system was demonstrated by using the scanning vibrating electrode technique.

Dr. Katja Skorb (Max Planck Institut of Colloids and Interfaces) and Dr. Daria Andreeva (University of Bayreuth) developed a one-step method to produce metal nanocomposites from metal alloys under ultrasound irradiation. Systematic investigation of ultrasound effects on various metal particles reveals cavitation-induced recrystallization and oxidation of metals as main factors in the process. The fact that different metals react in dramatically different fashion towards ultrasound irradiation was exploited for the formation of nanoscale composites. The application of the novel mesoporous nanocomposites as effective nanocatalysts is published in ChemComm:

Novel imaging layer technology for electron-beam and extreme-ultraviolet lithographic processes based upon the generation of Pd nanoparticles in Pd2+-loaded TiO2 films is being developed by scientists in Belarus, Switzerland and Germany. The team's approach permits switching from negative to positive imaging during pattern generation, which could open up fresh opportunities for the formation of schemotechnical elements of complex structures.

"Ultrasound processes are particularly interesting for a great variety of applications like formation of developed surfaces, finishing, catalyst formation, polymerization and surface polymer attachment, etc," Dr. Skorb, Dr. Andreeva and colleagues report.

"Here, we report on the ultrasound-driven formation of metal surface nanofoams in aqueous media. Systematic investigation of ultrasound effects on various types of aluminium, iron and magnesium alloys shows that the character of the metal determines the roughness of the metal surface," said Dr. Skorb.

The researchers concluded: "A trick with attachment of layered double hydroxide laurate to ananostructured aluminium-based foam surface results in the formation of a corrosion-resistant superhydrophobic surface...

Ultrasound processes are particularly interesting for a great variety of applications like formation of developed surfaces, finishing, catalyst formation, polymerization and surface polymer attachment, etc. Here, we report on the ultrasound-driven formation of metal surface nanofoams in aqueous media. Systematic investigation of ultrasound effects on various types of aluminium, iron and magnesium alloys shows that the character of the metal determines the roughness of the metal surface. A trick with attachment of layered double hydroxide laurate to a nanostructured aluminium-based foam surface results in the formation of a corrosion-resistant superhydrophobic surface.